DE202015105466U1 - stent - Google Patents

Abstract

A stent having a tubular braid structure (3) of interwoven wire strands (1, 2), wherein at least one first strand of wire (1) is formed by at least two strands (1.1, 1.2) extending adjacent to each other and contacting each other, the first strand of wire (1) helically wound in a first direction about an axis of rotation of the braid structure (3) and crossing at least one second wire strand (2) having at least one individual wire (2.1) and helically in a second direction about the axis of rotation of the braid structure (3) and at least one single wire (1.1) of the first wire strand (1) comprises a radiopaque core material encased in a cladding material having a lower radiopacity than the core material.

Description

The invention relates to a stent having a tubular braid structure of interwoven strands of wire, wherein at least a first strand of wire is formed by at least two individual wires which extend adjacent to each other and touch each other, wherein the first strand of wire helically winds in a first direction about an axis of rotation of the mesh structure and at least one second wire strand having at least a single wire and helically wound in a second direction about the axis of rotation of the braid structure, and wherein at least one individual wire of the first wire strand has a radiopaque core material which is sheathed with a sheath material having a lower radiopacity than having the core material. Such a wire of core material and cladding material is referred to as DFT wire.

The advantage of the invention is that position monitoring during the implantation of the stent can take place through the radiopaque core material. In this case, the stent is recognizable over its entire length, which facilitates the positioning, in particular in curved vessel sections. The combination of at least two wires to a first wire strand simultaneously results in an improved stability of the mesh structure.

The first wire strand may consist of only two individual wires in preferred embodiments. The second wire strand may consist of only a single wire. In general, not all wire strands wound in the same direction about the axis of rotation of the braid structure must have the same number of strands. Rather, the first wire strands can extend helically around the axis of rotation of the braided structure in a different winding direction and crossing each other in an intersecting manner. For example, four first strands of wire may be provided interlaced between second strands of wire, with each of two of the four first strands of wire being wound in different directions about the axis of rotation of the braid structure.

In a preferred embodiment of the stent it is provided that at least two, in particular both, wires of the first wire strand are formed as DFT wires, i. have a radiopaque core material, which is coated with a less radiopaque cladding material. This increases the radiopacity of the braid structure. The jacket material preferably has a shape memory material, in particular a nickel-titanium alloy.

The braid structure may comprise a total of four or six or ten, preferably eight, DFT wires. In particular, all the individual wires of the first wire strand may comprise a radiopaque core material which is sheathed with a sheath material having a lower radiopacity than the core material. It is particularly preferred if all the individual wires, in particular all the individual wires of all the wire strands which form the mesh structure, are formed as DFT wires.

The braid structure preferably has a conical or cylindrical outer contour. It is also possible that the mesh structure has a cylindrical portion and one or more conical or frusto-conical portions. In particular, the mesh structure may have frusto-conical end portions which are interconnected by a cylindrical portion.

Furthermore, it can be provided that the wire strands form a deflection at one longitudinal end of the braid structure, wherein the wire strands are wound before the deflection in a first direction about the longitudinal axis of the braid structure, and wherein the wire strands after the deflection in a second, in particular opposite, direction wound around the longitudinal axis of the braid structure. The deflection essentially forms an end loop of the mesh structure.

The cross-sectional area of the X-ray-visible core material may be about 20% to 40%, especially 30%, of the total cross-section of the DFT wire (core material plus cladding material) if the core material is platinum or platinum-iridium, and about 10% to 20%, if the nuclear material is tantalum.

It is preferably provided that for DFT wires having a diameter of 35 μm (after polishing), about 14% to 16%, in particular 15.1%, of the cross-sectional area of the X-ray-visible material, preferably a platinum-iridium alloy , is taken. For DFT wires having a diameter of 43 μm (after polishing), the cross-sectional area fraction of the X-ray-visible material, in particular the platinum-iridium alloy, is preferably about 27% to 29%, in particular 28.1%.

The stent, in particular the braid structure, is preferably suitable for delivery via a catheter having an inside diameter of about 0.42 mm (0.17 inches). Accordingly, the cross-sectional diameter of the stent is adjusted in the compressed state. In the expanded state, the stent may have a cross-sectional diameter of 3.5 mm. Such a stent with an expanded Cross-sectional diameter of 3.5 mm preferably consists of a total of 18 wire strands.

The wire strands may be deflected at one longitudinal end of the braid structure or form a deflection and be returned in an opposite direction to an opposite longitudinal end. At an opposite longitudinal end of the braid structure preferably open wire ends are arranged ( 1 ). Although 18 wire strands are used to form the braid structure, the braid structure then appears to consist of twice the wire strand number, namely 36 strands of wire. It is also possible that the mesh structure to form a stent having an expanded cross-sectional diameter of 3.5 mm appears to consist of 32 or 40 strands of wire, but is actually formed by interlacing and diverting 16 or 20 strands of wire.

For a stent having an expanded cross-sectional diameter of 3.0 mm or 2.5 mm, the braid structure is preferably formed from 16 strands of wire which are deflected and braided back at one longitudinal end of the braid structure. The braid structure then seems to consist of 32 wire strands because of the one-sided deflection of the wire strands. Alternatively, in such a stent, the expanded cross sectional diameter of which may be 3.0mm or 2.5mm, the braid structure may appear to consist of 24 or 36 strands of wire, in effect requiring only 12 or 18 strands of wire to form the braid structure which is longitudinally deflected and braided back.

It is preferred if a total of eight DFT wires are provided, which have a cross-sectional diameter between 40 .mu.m and 45 .mu.m, in particular 43 .mu.m, and form a total of four first wire strands. Because of the deflection of the four wire strands at one longitudinal end of the braid structure, the braid structure appears to be formed of eight strands of wire, each with two DFT wires. The remaining, in particular second, wire strands can each have a single individual wire, which has a cross-sectional diameter of 35 μm. This is in the 2 and 3 recognizable.

It can also be provided that the mesh structure has two or six or ten first wire strands. In general, the cross-sectional diameter of the individual wires that are not formed as DFT wires may be 35 μm or 30 μm or 40 μm. It is also conceivable that all individual wires are each designed as a DFT wire.

The braiding used can be 1 over 2. This means that a wire strand that is wound in a first direction about a longitudinal axis of the mesh structure, in each case two wire strands crossed and the subsequent two strands of wire crossed. The 1-over-2 wickerwork is in 2 respectively. 3 recognizable.

The braid angle, i. the angle at which the wire strands wound in opposite directions about the rotation axis of the mesh structure is preferably 140 ° in a central portion of the mesh structure. Each wire strand thus includes an angle of 70 ° with the longitudinal axis of the braid structure. During the transition to a deflection or end loop at a longitudinal end of the braided structure, the braiding angle is preferably about 130 °. At this point, the respective wire strand thus forms an angle of 65 ° with the longitudinal axis of the braid structure.

As additional X-ray markers crimped sleeves may be provided at the ends. Advantageously, one, two or three x-ray markers are arranged at each longitudinal end of the mesh structure. The x-ray markers can be formed by crimp sleeves which are each crimp-connected to a single wire or a wire strand of several, in particular two, individual wires.

The stent preferably has a length between 10 mm and 25 mm, preferably between 15 mm and 20 mm.

The stent is suitable for the treatment, in particular for Strömungsabschottung, of aneurysms in arteries. The surface of the wires is preferably coated corrosion-inhibiting. One or both stent ends may be atraumatically formed by forming end loops. The stent is preferably retractable into a catheter. One or both stent ends may be flaring, i. a diameter extension (frustoconical expansion) include.

For feeding the stent into a blood vessel, the stent, in particular the braid structure, can be connectable to a transporting wire. The connection can in particular be produced in a form-fitting manner. The connection can be designed so that the stent is fixed in a form-fitting manner to the transport wire in the compressed state, wherein the connection is released automatically upon expansion of the stent. The transport wire preferably has a flexible tip. The flexible tip may also be curved to act atraumatic. This is in 4 shown by way of example.

The attached drawings show the following:

1 a side view of a stent according to a preferred embodiment of the present invention;

2 a detailed view of a central portion of the mesh structure of the stent after 1 ;

3 a detailed view of an end portion of the mesh structure of the stent after 1 ; and

4 a partial perspective view of the stent after 1 with a transport wire for delivery of the stent into a blood vessel.

The reference numerals in the drawings are assigned the following components / elements of the invention:

LIST OF REFERENCE NUMBERS

1

denotes a first wire strand of the mesh structure,

2

denotes a second wire strand of the mesh structure,

1.1

denotes a first single wire, which is designed as a DFT wire,

1.2

denotes a second individual wire, which is designed as a DFT wire,

3

denotes the mesh structure,

4

denotes a deflection or end loop,

5

denotes a transport wire, and

6

denotes a flexible, bent tip of the transport wire.

Claims (7)

Stent having a tubular braid structure ( 3 ) of interwoven wire strands ( 1 . 2 ), wherein at least one first wire strand ( 1 ) by at least two individual wires ( 1.1 . 1.2 ), which run next to each other and touch each other, wherein the first wire strand ( 1 helically in a first direction about an axis of rotation of the braid structure ( 3 ) winds and at least one second wire strand ( 2 ) crossing at least one single wire ( 2.1 ) and helically in a second direction about the axis of rotation of the braid structure ( 3 ) and at least one individual wire ( 1.1 ) of the first wire strand ( 1 ) has a radiopaque core material encased in a cladding material having lower radiopacity than the core material. Stent according to claim 1, characterized in that at least two, in particular both, individual wires ( 1.1 . 1.2 ) of the first wire strand ( 1 ) comprise a radiopaque core material encased in a cladding material having a lower radiopacity than the core material. Stent according to claim 1 or 2, characterized in that all the individual wires ( 1.1 . 1.2 ) of the first wire strand ( 1 ) comprise a radiopaque core material encased in a cladding material having a lower radiopacity than the core material. Stent according to one of the preceding claims, characterized in that the individual wires ( 1.1 . 1.2 ) of all wire strands ( 1 . 2 ) comprise a radiopaque core material encased in a cladding material having a lower radiopacity than the core material. Stent according to one of the preceding claims, characterized in that the braid structure ( 3 ) has a conical or cylindrical outer contour. Stent according to one of the preceding claims, characterized in that the wire strands ( 1 . 2 ) form a deflection at one longitudinal end of the braid structure, wherein the wire strands ( 1 . 2 ) before the diversion ( 4 ) in a first direction about the longitudinal axis of the braid structure ( 3 ) and the wire strands ( 1 . 2 ) after the diversion ( 4 ) in a second direction about the longitudinal axis of the braid structure ( 3 ) are wound. Stent according to one of the preceding claims, characterized in that the jacket material comprises a shape memory material, in particular a nickel-titanium alloy.

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